August Belmont (December 8, 1816 - November 24, 1890), American banker and financier, was born at Alzei, Rhenish Prussia.

He entered the banking house of the Rothschild family at Frankfort at the age of fourteen, acted as their agent for a time at Naples, and in 1837 settled in New York as their American representative. He became an American citizen, and married a daughter of Commodore Matthew C Perry. He was the consul-general of Austria at New York from 1844 to 1850, when he resigned in protest against Austria's treatment of Hungary.

In 1853-1855 he was chargé d'affaires for the United States at the Hague, and from i855 to 1858 was tile American minister resident there. In 1860 he was a delegate to the Democratic National Convention at Charleston, South Carolina, actively supporting Stephen A Douglas for the presidential nomination, and afterwards joining those who withdrew to the convention at Baltimore, Maryland, where he was chosen chairman of the National Democratic Committee .

He energetically supported the Union cause during the Civil War, and exerted a strong influence in favour of the North upon the merchants and financiers of England and France. He remained at the head of the Democratic organization until 1872. He died in New York on the 24th of November 1890. His sons Oliver and August were also notable.

A volume entitled Letters, Speeches and Addresses of August Belmont (the elder) was published at New York in 1890.